1. Field of the Invention
The present invention relates to a navigation terminal mounted on a movable body and a navigation system including the terminal.
2. Description of the Related Art
A car navigation system mounted on a vehicle that is a typical movable body displays a map on a display unit based on a current location of the vehicle determined, with a mark indicating the current location of the vehicle superposed on the map.
In the car navigation system, a positioning unit for determining the current location of the vehicle includes a GPS (Global Positioning System) receiver and various autonomous navigation sensors for calculating the current location from a travel distance and a moving direction of the vehicle. Also, map information for displaying the map on the display unit, relevant information associated with the map information and various kinds of functional services are provided from an information center located outside the vehicle, utilizing a communication unit mounted on the vehicle.
One of the functional services is a location confirmation service. A mobile terminal mounted on each of a plurality of vehicles transmits information indicating the current location to the information center, and the information center stores the received information indicating the current location of each vehicle with identification information for identifying each vehicle. In response to a request signal from a mobile terminal of one vehicle, the information center transmits the information indicating the current locations of other vehicles to the mobile terminal of the one vehicle. In this manner, the mobile terminal of the one vehicle can confirm the current locations of other vehicles.
Since such services require communication, it is necessary to suppress the communication costs taken to confirm the locations of other vehicles.
Also, it is not preferable that the confirmed locations of other vehicles show locations of other vehicles at an older time than the confirmation time.